2009-04-09 Robert Dewar <dewar@adacore.com>

        * checks.adb:
        (Insert_Valid_Check): Avoid unnecessary generation of junk declaration
        when no invalid values exist, Avoid duplicate read of atomic variable.

        * cstand.adb (Build_Signed_Integer_Type): Set Is_Known_Valid
        (Standard_Unsigned): Set Is_Known_Valid

        * sem_ch3.adb (Analyze_Subtype_Declaration): Copy Is_Known_Valid on
	subtype declaration if no constraint.
        (Set_Modular_Size): Set Is_Known_Valid if appropriate
        (Build_Derived_Numeric_Type): Copy Is_Known_Valid if no constraint



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@145836 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 11 insertions, 1 deletions

diff --git a/gcc/ada/checks.adb b/gcc/ada/checks.adb
index da6ca2e68c8..45462db72b5 100644
--- a/gcc/ada/checks.adb
+++ b/gcc/ada/checks.adb
@@ -5125,10 +5125,12 @@ package body Checks is
       Exp : Node_Id;
 
    begin
-      --  Do not insert if checks off, or if not checking validity
+      --  Do not insert if checks off, or if not checking validity or
+      --  if expression is known to be valid
 
       if not Validity_Checks_On
         or else Range_Or_Validity_Checks_Suppressed (Expr)
+        or else Expr_Known_Valid (Expr)
       then
          return;
       end if;
@@ -5152,6 +5154,14 @@ package body Checks is
       begin
          Set_Do_Range_Check (Exp, False);
 
+         --  Force evaluation to avoid multiple reads for atomic/volatile
+
+         if Is_Entity_Name (Exp)
+           and then Is_Volatile (Entity (Exp))
+         then
+            Force_Evaluation (Exp, Name_Req => True);
+         end if;
+
          --  Insert the validity check. Note that we do this with validity
          --  checks turned off, to avoid recursion, we do not want validity
          --  checks on the validity checking code itself!